U.S. patent application number 15/922182 was filed with the patent office on 2018-07-19 for optical laminate, polarizing plate, method of manufacturing polarizing plate, and image display device.
This patent application is currently assigned to FUJIFILM Corporation. The applicant listed for this patent is FUJIFILM Corporation. Invention is credited to Junichi HIRAKATA, Makoto KAMO, Hideki KANEIWA.
Application Number | 20180200988 15/922182 |
Document ID | / |
Family ID | 58386845 |
Filed Date | 2018-07-19 |
United States Patent
Application |
20180200988 |
Kind Code |
A1 |
KANEIWA; Hideki ; et
al. |
July 19, 2018 |
OPTICAL LAMINATE, POLARIZING PLATE, METHOD OF MANUFACTURING
POLARIZING PLATE, AND IMAGE DISPLAY DEVICE
Abstract
An object of the invention is to provide an optical laminate
which has excellent workability in the production of a polarizing
plate and is capable of suppressing the occurrence of cracks in the
polarizing plate, a polarizing plate, a method of manufacturing the
polarizing plate using the optical laminate, and an image display
device having the polarizing plate. An optical laminate according
to the invention has a polarizer, an optical anisotropic layer, and
a masking layer in this order, and hardness HB of the masking layer
and hardness HA of a layer adjacent to the optical anisotropic
layer side of the masking layer satisfy Expression (1):
HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1).
Inventors: |
KANEIWA; Hideki; (Kanagawa,
JP) ; KAMO; Makoto; (Kanagawa, JP) ; HIRAKATA;
Junichi; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
FUJIFILM Corporation
Tokyo
JP
|
Family ID: |
58386845 |
Appl. No.: |
15/922182 |
Filed: |
March 15, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2016/077954 |
Sep 23, 2016 |
|
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15922182 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 1/133528 20130101;
G02B 5/3083 20130101; B32B 7/02 20130101; G02B 5/3016 20130101;
B32B 27/365 20130101; G02F 1/1335 20130101; G02B 1/00 20130101;
G02B 5/3033 20130101; G02B 5/305 20130101; G02F 1/13363 20130101;
G02F 2201/50 20130101; G02F 2001/133541 20130101; G02B 1/14
20150115 |
International
Class: |
B32B 7/02 20060101
B32B007/02; G02B 5/30 20060101 G02B005/30; G02F 1/1335 20060101
G02F001/1335; G02B 1/14 20060101 G02B001/14; B32B 27/36 20060101
B32B027/36 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 25, 2015 |
JP |
2015-188817 |
Claims
1. An optical laminate comprising in order: a polarizer; an optical
anisotropic layer; and a masking layer, wherein hardness HB of the
masking layer and hardness HA of a layer adjacent to the optical
anisotropic layer side of the masking layer satisfy Expression (1),
HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1)
2. A polarizing plate comprising in order: a polarizer; an optical
anisotropic layer; and a masking layer, wherein the masking layer
is provided in a peripheral portion of a layer adjacent to the
optical anisotropic layer side of the masking layer, and hardness
HB of the masking layer and hardness HA of the layer adjacent to
the optical anisotropic layer side of the masking layer satisfy
Expression (1), HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1)
3. A method of manufacturing a polarizing plate to produce the
polarizing plate according to claim 2, comprising: a cutting step
of cutting the optical laminate according to claim 1 in a thickness
direction to produce the polarizing plate.
4. The method of manufacturing a polarizing plate according to
claim 3, further comprising: a patterning step of removing a part
of the masking layer in a portion which is not cut in the cutting
step before or after the cutting step.
5. An image display device comprising: the polarizing plate
according to claim 2; and a display element.
6. An image display device comprising: a liquid crystal cell; and a
pair of polarizing plates between which the liquid crystal cell is
interposed, wherein at least one of the pair of polarizing plates
which is disposed on the visible side is the polarizing plate
according to claim 2.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of PCT International
Application No. PCT/JP201.6/077954 filed on Sep. 23, 2016, which
claims priority under 35 U.S.C. .sctn. 119(a) to Japanese Patent
Application No. 2015-188817 filed on Sep. 25, 2015. The above
application is hereby expressly incorporated by reference, in its
entirety, into the present application.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to an optical laminate, a
polarizing plate, a method of manufacturing the polarizing plate,
and an image display device having the polarizing plate.
2. Description of the Related Art
[0003] In image display devices (e.g., liquid crystal display
devices), it is necessary to secure a non-display region in a
peripheral portion in order to arrange a gate driver and a source
driver.
[0004] In the non-display region of the peripheral portion, a
masking layer which is generally called a design layer, a colored
layer, a printed layer, or the like is provided from the viewpoint
of design.
[0005] For example, in JP2014-238533A, an optical member which has
a front plate, a smoothing layer, a polarizer, and a retardation
film in this order, and in which a printed layer is formed in a
peripheral portion of a surface of the front plate on the smoothing
layer side is described as an optical member which is used in an
image display device ([claim 1], [FIG. 1]).
SUMMARY OF THE INVENTION
[0006] In recent years, with a reduction in the thickness of image
display devices, especially, small- and medium-sized liquid crystal
display devices, the thickness of a member (e.g., a polarizing
plate) to be used therein is also required to be reduced.
[0007] Accordingly, the inventors have considered a configuration
without a front plate from the viewpoint of thickness reduction in
regard to an optical member (optical laminate) having a masking
layer described in JP2014-238533A or the like. However, it has been
found that in a case where the front plate is simply removed,
problems occur such as chipping of the masking layer or smoothing
of a portion in which the masking layer is provided.
[0008] Therefore, the inventors have considered providing a masking
layer on the inner side (that is, on the display element (e.g.,
liquid crystal cell) side) of a polarizer (in a liquid crystal
display device, a polarizer on the visible side). However, it has
been found that workability deteriorates in the production of a
polarizing plate by cutting the optical laminate, and thus a new
problem occurs such as the occurrence of cracks between the masking
layer and a layer adjacent to the masking layer in the produced
polarizing plate.
[0009] Accordingly, an object of the invention is to provide an
optical laminate which has excellent workability in the production
of a polarizing plate and is capable of suppressing the occurrence
of cracks in the polarizing plate, a polarizing plate, a method of
manufacturing the polarizing plate using the optical laminate, and
an image display device having the polarizing plate.
[0010] The inventors have conducted intensive studies in order to
achieve the object, and found that regarding an optical laminate
having a polarizer, an optical anisotropic layer, and a masking
layer in this order, in a case where hardness HB of the masking
layer is half to two times hardness HA of a layer adjacent to the
optical anisotropic layer side of the masking layer, workability in
the production of a polarizing plate is improved and the occurrence
of cracks in the polarizing plate can be suppressed, whereby the
inventors completes the invention.
[0011] That is, the inventors have found that the object can be
achieved with the following configuration.
[0012] [1] An optical laminate comprising in order: a polarizer; an
optical anisotropic layer; and a masking layer, in which hardness
HB of the masking layer and hardness HA of a layer adjacent to the
optical anisotropic layer side of the masking layer satisfy
Expression (1).
HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1)
[0013] [2] A polarizing plate comprising in order: a polarizer; an
optical anisotropic layer; and a masking layer, in which the
masking layer is provided in a peripheral portion of a layer
adjacent to the optical anisotropic layer side of the masking
layer, and hardness HB of the masking layer and hardness HA of the
layer adjacent to the optical anisotropic layer side of the masking
layer satisfy Expression (1).
HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1)
[0014] [3] A method of manufacturing a polarizing plate to produce
the polarizing plate according to [2], comprising: a cutting step
of cutting the optical laminate according to [1] in a thickness
direction to produce the polarizing plate.
[0015] [4] The method of manufacturing a polarizing plate according
to [3], further comprising: a patterning step of removing a part of
the masking layer in a portion which is not cut in the cutting step
before or after the cutting step.
[0016] [5] An image display device comprising: the polarizing plate
according to [2]; and a display element.
[0017] [6] An image display device comprising: a liquid crystal
cell; and a pair of polarizing plates between which the liquid
crystal cell is interposed, in which at least one of the pair of
polarizing plates which is disposed on the visible side is the
polarizing plate according to [2].
[0018] According to the invention, it is possible to provide an
optical laminate which has excellent workability in the production
of a polarizing plate and is capable of suppressing the occurrence
of cracks in the polarizing plate, a polarizing plate, a method of
manufacturing the polarizing plate using the optical laminate, and
an image display device having the polarizing plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1A is a cross-sectional view schematically illustrating
an embodiment of an optical laminate according to the
invention.
[0020] FIG. 1B is a cross-sectional view schematically illustrating
another embodiment of the optical laminate according to the
invention.
[0021] FIG. 2 is a cross-sectional view schematically illustrating
an embodiment of a polarizing plate according to the invention.
[0022] FIG. 3 is a schematic diagram explaining a method of
manufacturing a polarizing plate using the optical laminate of FIG.
1B (cutting step).
[0023] FIG. 4 is a schematic diagram explaining a method of
manufacturing a polarizing plate using the optical anisotropic
layer of FIG. 1A (cutting step and patterning step).
[0024] FIG. 5 is a cross-sectional view schematically illustrating
an embodiment of an image display device according to the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Hereinafter, the invention will be described in detail.
[0026] The following description of constituent requirements is
based on typical embodiments of the invention, but the invention is
not limited thereto.
[0027] In this specification, a numerical value range expressed
using "to" means a range including numerical values before and
after "to" as a lower limit value and an upper limit value.
[0028] Regarding the angle, each of "perpendicular" and "parallel"
means a range of strict angle.+-.10.degree., and regarding the
angle, "the same" and "different" can be determined based on
whether the angular difference is less than 5.degree. or not.
[0029] In this specification, "visible light" is light ranging from
380 to 780 nm. In this specification, the measurement wavelength is
550 nm in a case where there are no particular additional notes in
regard to the measurement wavelength.
[0030] Next, terms which are used in this specification will be
described.
[0031] <Slow Axis>
[0032] In this specification, a "slow axis" means a direction in
which a refractive index is maximized in a plane. A slow axis of an
optical anisotropic layer means a slow axis of the entire optical
anisotropic layer.
[0033] <Re (.lamda.), Rth (.lamda.)>
[0034] In this specification, "Re (.lamda.)" and "Rth (.lamda.)"
represent in-plane retardation and retardation in a thickness
direction, respectively, at a wavelength .lamda..
[0035] Re (.lamda.) is measured by making light having a wavelength
of .lamda. nm incident in a normal direction of a film by KOBRA
21ADH or KOBRA WR (all manufactured by Oji Scientific Instruments).
In the selection of the measurement wavelength .lamda. nm, a
wavelength selective filter can be manually exchanged or the
measurement value can be exchanged by the program to perform the
measurement.
[0036] Herein, in a case where a film to be measured is expressed
as a uniaxial or biaxial index ellipsoid, Rth (.lamda.) is
calculated through the following method.
[0037] Rth (.lamda.) is calculated by KOBRA 21ADH or KOBRA WR based
on Re(.lamda.) values which are retardation values measured at a
total of six points by making light having a wavelength of k nm
incident in directions tilted up to 50 degrees toward a single side
at 10 degree intervals with respect to the normal direction of the
film, using an in-plane slow axis (determined by KOBRA 21ADH or
KOBRA WR) as a tilt axis (rotational axis) (in a case where there
is no slow axis, an arbitrary direction in the film plane is used
as the rotational axis), an assumed average refractive index, and a
value input as a film thickness.
[0038] In the above description, in a case of a film having a
direction in which the retardation value reaches zero at a certain
tilt angle from the normal direction using the in-plane slow axis
as a rotational axis, the retardation value at a tilt angle larger
than the above-described tilt angle is changed into a negative
value, and then calculated by KOBRA 21ADH car KOBRA WR.
[0039] Meanwhile, Rth can also be calculated as follows:
retardation values are measured in two arbitrary tilt directions
using the slow axis as a tilt axis (rotational axis) (in a case
where there is no slow axis, an arbitrary direction in the film
plane is used as the rotational axis), and Rth is calculated based
on the above-described values, an assumed average refractive index,
and a value input as a film thickness using Expressions (1) and
(2).
Re ( .theta. ) = [ nx - ny .times. nz ( { ny sin ( sin - 1 ( sin (
- .theta. ) nx ) ) } 2 + { nz cos ( sin - 1 ( sin ( - .theta. ) nx
) ) } 2 ) ] .times. d cos { sin - 1 ( sin ( - .theta. ) nx ) }
Expression ( 1 ) Rth = [ nx + ny 2 - nz ] .times. d Expression ( 2
) ##EQU00001##
[0040] In the expressions, Re (.theta.) represents a retardation
value in a direction tilted at an angle .theta. from the normal
direction. nx represents a refractive index in a slow axis
direction in the plane, ny represents a refractive index in a
direction perpendicular to nx in the plane, and nz represents a
refractive index in a direction perpendicular to nx and ny. d
represents a film thickness.
[0041] In a case where a film to be measured cannot be expressed as
a uniaxial or biaxial index ellipsoid, that is, does not have a
so-called optic axis, Rth (.lamda.) is calculated through the
following method.
[0042] Rth (.lamda.) is calculated by KOBRA 21ADH or KOBRA WR based
on Re(.lamda.) values which are retardation values measured at a
total of eleven points by making light having a wavelength of
.lamda. nm incident in directions tilted from -50 degrees to +50
degrees at 10 degree intervals with respect to the normal direction
of the film, using an in-plane slow axis (determined by KOBRA 21ADH
or KOBRA WR) as a tilt axis (rotational axis), an assumed average
refractive index, and a value input as a film thickness.
[0043] In the above measurement, as the assumed average refractive
index, values from a polymer handbook (JOHN WILEY & SONS, INC)
and a variety of optical film catalogues can be used. For optical
films having unknown average refractive index values, the
refractive index values can be measured using an Abbe
refractometer. The average refractive index values of major optical
films will be described below: cellulose acylate (1.48),
cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl
methacrylate (1.49), and polystyrene (1.59). By inputting these
assumed average refractive index values and the film thickness,
KOBRA 21ADH or KOBRA WR calculates nx, ny, and nz. With the
calculated nx, ny, and nz, Nz=(nx-nz)/(nx-ny) is further
calculated.
[0044] [Optical Laminate]
[0045] An optical laminate according to the invention has a
polarizer, an optical anisotropic layer, and a masking layer in
this order.
[0046] In the optical laminate according to the invention, hardness
HB of the masking layer and hardness HA of a layer adjacent to the
optical anisotropic layer side of the masking layer (hereinafter,
may be simply abbreviated as "adjacent layer") satisfy Expression
(1).
HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1)
[0047] Here, regarding the "layer adjacent to the optical
anisotropic layer side of the masking layer" (adjacent layer), for
example, in a case where an arbitrary polymer film is provided
between the masking layer and the optical anisotropic layer, and
the masking layer and the polymer film are adjacent to each other,
the adjacent layer is the polymer film, and in a case where the
masking layer and the optical anisotropic layer are adjacent to
each other, the adjacent layer is the optical anisotropic
layer.
[0048] As both the hardness HB of the masking layer and the
hardness HA of the adjacent layer, Martens hardness values obtained
by a nano-indentation method according to ISO 1457 are used. More
specifically, using a microhardness tester (e.g., DUH-211 of
Shimadzu Corporation or HM2000 of FISCHER INSTRUMENTS K.K.)
provided with a Berkovich indenter, the indenter is pushed against
a cross-section obtained by cutting a measurement target layer by a
microtome at a pushing speed of 10 mN/min until the maximum test
force of 20 mN is reached, and based on a value of the maximum
pushing depth in a case where unloading is conducted after holding
for a certain period of time, a value is obtained from the
following expression and used.
HM=F/(26.43.times.h.sup.2)
[0049] In the expression, HM represents Martens hardness (unit:
N/mm.sup.2), F represents the maximum test force (unit: N), and h
represents a pushing depth (unit: mm).
[0050] In the invention, in a case where the hardness HB of the
masking layer and the hardness HA of the adjacent layer satisfy
Expression (1), excellent workability is obtained in the production
of a polarizing plate, and the occurrence of cracks in the
polarizing plate can be suppressed.
[0051] The detailed reason for this is not clear, but the inventors
presume the reason to be as follows.
[0052] That is, the reason is thought to be that since the
difference between the hardness HB of the masking layer and the
hardness HA of the adjacent layer is small, stress is not
concentrated on any one layer, but appropriately distributed during
the cutting step for producing a polarizing plate, and it is
possible to gently absorb the stress.
[0053] In the invention, the hardness HB of the masking layer and
the hardness HA of the adjacent layer preferably satisfy Expression
(2) since the workability in the production of a polarizing plate
is further improved.
HA.times.0.75.ltoreq.HB.ltoreq.HA.times.1.4 (2)
[0054] Next, an overall configuration of the optical laminate
according to the invention will be described using FIGS. 1A and 1B,
and then configurations of the respective portions will be
described in detail.
[0055] Each of FIGS. 1A and 1B is a cross-sectional view
schematically illustrating an embodiment of the optical laminate
according to the invention.
[0056] As illustrated in FIGS. 1A and 1B, an optical laminate 10
has a polarizer 1, an optical anisotropic layer 2, and a masking
layer 3 in this order.
[0057] As illustrated in FIGS. 1A and 1B, an arbitrary polymer film
4 may be provided between the polarizer 1 and the optical
anisotropic layer 2, and an arbitrary polymer film 5 may be
provided on a surface of the polarizer 1 on the side opposite to
the polymer film 4.
[0058] The optical laminate according to the invention may have an
arbitrary polymer film (not shown) between the optical anisotropic
layer 2 and the masking layer 3 illustrated in FIGS. 1A and 1B, or
an arbitrary hard coat layer (not shown) on a surface of the
polymer film 5 on the side opposite to the polarizer 1.
[0059] In die optical laminate according to the invention, the
masking layer 3 may be provided on the entire surface of the
adjacent layer (in FIG. 1A, optical laminate 2) as illustrated in
FIG. 1A, or the masking layer 3 may be provided on a part of the
optical laminate 2 as illustrated in FIG. 1B.
[0060] [Polarizer]
[0061] A polarizer which is used in the invention is not
particularly limited, and a conventionally known polarizer can be
appropriately employed and used.
[0062] Examples of the polarizer include a film obtained by
uniaxially stretching a hydrophilic polymer film such as a
polyvinyl alcohol-based film, a partially formalized polyvinyl
alcohol-based film, or an ethylene-vinyl acetate copolymer-based,
partially saponified film after adsorption of a dichroic substance
such as iodine or a dichroic dye to the hydrophilic polymer film;
and a polyene-based alignment film such as a dehydrate of polyvinyl
alcohol or a dehydrochlorinate of polyvinyl chloride.
[0063] Among these, a polarizer formed of a polyvinyl alcohol-based
film and a dichroic substance such as iodine is suitable.
[0064] The thickness of the polarizer is not particularly limited.
The thickness is preferably 25 .mu.tri or less, and more preferably
15 .mu.m or less since the thickness of a polarizing plate can be
reduced. The lower limit is not particularly limited, and generally
1 .mu.m or greater.
[0065] [Optical Anisotropic Layer]
[0066] An optical anisotropic layer which is used in the invention
is not particularly limited, and a conventionally known optical
anisotropic layer can be appropriately used.
[0067] In the invention, the optical anisotropic layer preferably
includes a liquid crystal compound. The optical anisotropic layer
may have a single layer structure or a lamination structure.
[0068] <Liquid Crystal Compound>
[0069] In general, liquid crystal compounds can be classified into
a rod-like type and a disk-like type according to the shape
thereof. Further, each type includes a low molecular type and a
high molecular type. The term high molecular generally refers to a
compound having a degree of polymerization of 100 or greater
(Polymer Physics-Phase Transition Dynamics, written by Masao Doi,
p. 2, published by Iwanami Shoten, 1992). In the invention, any
type of liquid crystal compound can be used, but a rod-like liquid
crystal compound or a discotic liquid crystal compound (disk-like
liquid crystal compound) is preferably used. Two or more types of
rod-like liquid crystal compounds, two or more types of disk-like
liquid crystal compounds, or a mixture of a rod-like liquid crystal
compound and a disk-like liquid crystal compound may be used. In
order to fix the above-described liquid crystal compound, a
rod-like liquid crystal compound or disk-like liquid crystal
compound having a polymerizable group is more preferably used, and
the liquid crystal compound even more preferably has two or more
polymerizable groups in one molecule. In a case of a mixture of two
or more types of liquid crystal compounds, at least one type of
liquid crystal compound preferably has two or more polymerizable
groups in one molecule.
[0070] As the rod-like liquid crystal compound, for example, those
described in claim 1 of JP1999-513019A (JP-H11-513019A) or
paragraphs [0026] to [0098] of JP2005-289980A can be preferably
used, and as the discotic liquid crystal compound, for example,
those described in paragraphs [0020] to [0067] of JP2007-1.08732A
or paragraphs [0013] to [0108] of JP2010-244038A can be preferably
used, but the liquid crystal compounds are not limited thereto.
[0071] In the invention, the optical anisotropic layer in the
optical laminate preferably satisfies Expression (I) from the
viewpoint that a polarizing plate according to the invention to be
described later is allowed to function as a circularly polarizing
plate.
100.ltoreq.Re(550).ltoreq.180 nm (1)
[0072] Here, in Expression (I), Re (550) represents in-plane
retardation of the optical anisotropic layer at a wavelength of 550
nm.
[0073] In this specification, the "circularly polarizing plate" is
used to mean both of a long circularly polarizing plate and a
circularly polarizing plate cut into a size that fits in a display
device unless specifically noted. The term "cut" mentioned herein
includes "punching" and "cutting".
[0074] In the invention, the optical anisotropic layer is
preferably a laminate having a .lamda./2 plate and a .lamda./4
plate since the optical anisotropic layer functions as a .lamda./4
plate in a wide wavelength range and can be more suitably used as a
circularly polarizing plate.
[0075] <.lamda./2 Plate>
[0076] A .lamda./2 plate refers to an optical anisotropic layer in
which in-plane retardation Re (.lamda.) at a specific wavelength of
.lamda. nm satisfies Re (.lamda.)=.lamda./2. The above expression
may be satisfied at one (e.g., 550 nm) of wavelengths of a visible
light region.
[0077] In the invention, in-plane retardation Re (550) of the
.lamda./2 plate at a wavelength of 550 nm is preferably 205 to 275
nm, and more preferably 215 to 265 nm.
[0078] Rth (550) that is a retardation value in a thickness
direction of the .lamda./2 plate measured at a wavelength of 550 nm
is preferably -240 to 240 nm, and more preferably -160 to 160 nm in
view of more excellent effects of the invention.
[0079] The thickness of the .lamda./2 plate is not particularly
limited, and preferably 0.5 to 10 .mu.m, and more preferably 0.5 to
5 .mu.m since the thickness of a display device can be easily
reduced.
[0080] The thickness means an average thickness. It is obtained by
arithmetically averaging thicknesses measured at arbitrary five
points of the .lamda./2 plate.
[0081] The .lamda./2 plate is more preferably formed using a liquid
crystal compound (rod-like liquid crystal compound or disk-like
liquid crystal compound) having a polymerizable group since a
change of optical characteristics due to the temperature or
humidity can be reduced. The liquid crystal compound may be a
mixture of two or more types, and in that case, at least one type
preferably has two or more polymerizable groups.
[0082] That is, the .lamda./2 plate is preferably a layer formed by
fixing a rod-like liquid crystal compound having a polymerizable
group or a disk-like liquid crystal compound having a polymerizable
group by polymerization, and in that case, after the formation of
the layer, it is not necessary for the layer to exhibit
crystallinity.
[0083] The type of the polymerizable group included in a rod-like
liquid crystal compound or a disk-like liquid crystal compound is
not particularly limited. A functional group allowing an addition
polymerization reaction is preferable, and a polymerizable
ethylenically unsaturated group or a cyclic polymerizable group is
preferable. More specifically, preferable examples thereof include
a (meth)acryloyl group, a vinyl group, a styryl group, and an allyl
group, and a (meth)acryloyl group is more preferable. A
(meth)acryloyl group means both of a methacryloyl group and an
acryloyl group.
[0084] <.lamda./4 Plate>
[0085] A .lamda./4 plate is a plate functioning to convert linearly
polarized light having a certain wavelength into circularly
polarized light (or to convert circularly polarized light into
linearly polarized light), and refers to an optical anisotropic
layer in which in-plane retardation Re (2L) at a certain wavelength
of .lamda. nm satisfies Re (.lamda.)=.lamda./4. The above
expression may be satisfied at one (e.g., 550 nm) of wavelengths of
a visible light region.
[0086] In the invention, in-plane retardation Re (550) of the
.lamda./4 plate at a wavelength of 550 nm is preferably 100 to 150
nm, and more preferably 110 to 140 nm.
[0087] Rth (550) that is a retardation value in a thickness
direction of the .lamda./4 plate measured at a wavelength of 550 nm
is preferably -120 to 120 nm, and more preferably -80 to 80 nm in
view of more excellent effects of the invention.
[0088] The thickness of the .lamda./4 plate is not particularly
limited, and preferably 0.5 to 10 .mu.m, and more preferably 0.5 to
5 .mu.m since the thickness of a display device can be easily
reduced.
[0089] The thickness means an average thickness. It is obtained by
arithmetically averaging thicknesses measured at arbitrary five
points of the .lamda./4 plate.
[0090] The .lamda./4 plate is preferably a layer formed by fixing a
liquid crystal compound (rod-like liquid crystal compound or a
disk-like liquid crystal compound) having a polymerizable group by
polymerization, and in that case, after the formation of the layer,
it is not necessary for the layer to exhibit crystallinity.
[0091] In the invention, in a case where a laminate having the
.lamda./2 plate and the .lamda./4 plate which have been described
above is used as an optical anisotropic layer, a circularly
polarizing plate preferably has the above-described polarizer, a
transparent support, the .lamda./2 plate, and the .lamda./4 plate
in this order to function as a circularly polarizing plate in a
wide wavelength range. In addition, an angle formed between an
in-plane slow axis of the .lamda./4 plate and an in-plane slow axis
of .lamda./2 plate is preferably 60.degree..
[0092] The method of forming the above-described .lamda./2 plate or
.lamda./4 plate is not particularly limited, and examples thereof
include known methods.
[0093] For example, a coating film may be formed by coating a
predetermined substrate (including any one of temporary substrate,
.lamda./2 plate, and .lamda./4 plate) with an optical anisotropic
layer forming composition (hereinafter, may be simply referred to
as "composition") containing a liquid crystal compound having a
polymerizable group, and the obtained coating film may be cured
(irradiation with ultraviolet rays (light irradiation treatment) or
heating treatment) for manufacturing. If necessary, an alignment
film to be described later may be used.
[0094] Coating with the composition can be performed by a known
method (e.g., wire bar coating method, extrusion coating method,
direct gravure coating method, reverse gravure coating method, or
die coating method).
[0095] The composition may contain a component other than the
above-described liquid crystal compound.
[0096] For example, the composition may contain a polymerization
initiator. A polymerization initiator to be used is selected in
accordance with the form of the polymerization reaction, and
examples thereof include a thermal polymerization initiator and a
photopolymerization initiator. Examples of the photopolymerization
initiator include .alpha.-carbonyl compound, acyloin ether,
.alpha.-hydrocarbon-substituted aromatic acyloin compound,
polynuclear quinone compound, and combination of triaryl imidazole
dimer and p-aminophenyl ketone.
[0097] The amount of the polymerization initiator to be used is
preferably 0.01 to 20 mass %, and more preferably 0.5 to 5 mass %
with respect to the total solid content of the composition.
[0098] The composition may contain a polymerizable monomer in view
of the uniformity of the coating film and the hardness of the
film.
[0099] Examples of the polymerizable monomer include a radical
polymerizable or cation polymerizable compound. A polyfunctional
radical polymerizable monomer is preferable, and the polymerizable
monomer is preferably copolymerizable with the above-described
liquid crystal compound containing a polymerizable group. Examples
thereof include those described in paragraphs [0018] to [0020] of
JP2002-296423A.
[0100] The amount of the polymerizable monomer to be added is
preferably 1 to 50 mass %, and more preferably 2 to 30 mass % with
respect to the total mass of the liquid crystal compound.
[0101] The composition may contain a surfactant in view of the
uniformity of the coating film and the hardness of the film.
[0102] Examples of the surfactant include conventional known
compounds, and a fluorine-based compound is preferable. Specific
examples thereof include compounds described in paragraphs [0028]
to [0056] of JP2001-330725A and compounds described in paragraphs
[0069] to [0126] of JP2003-295212.
[0103] The composition may contain a solvent. An organic solvent is
preferably used.
[0104] As the organic solvent, for example, an alcohol-based
solvent or a ketone-based solvent is preferably used.
[0105] Specific examples thereof include acetone, methyl ethyl
ketone, 2-pentanone, 3-pentanone, 2-hexane, 2-heptanone,
4-heptanone, methyl isopropyl ketone, ethyl isopropyl ketone,
diisopropyl ketone, methyl isobutyl ketone, methyl-t-butyl ketone,
diacetyl, acetylacetone, acetonylacetone, diacetone alcohol,
mesityl oxide, chloroacetone, cyclopentanone, cyclohexanone and
acetophenone. Among these, methyl ethyl ketone and methyl isobutyl
ketone are preferable. These solvents may be used alone or as a
mixture of at least two kinds thereof mixed at an arbitrary mixing
ratio.
[0106] The composition may contain various alignment agents such as
vertical alignment accelerators, e.g., polarizer interface-side
vertical alignment agents and air interface-side vertical alignment
agents, and horizontal alignment accelerators, e.g., polarizer
interface-side horizontal alignment agents and air interface-side
horizontal alignment agents.
[0107] The composition may further contain an adhesion enhancing
agent, a plasticizer, a polymer, or the like other than the
above-described components.
[0108] In the invention, the thickness of the optical anisotropic
layer (in a case where the layer has the .lamda./2 plate and the
.lamda./4 plate which have been described above, total thickness
thereof) is not particularly limited. The thickness is preferably
0.1 to 10 .mu.m, and more preferably 0.5 to 5 .mu.m.
[0109] [Masking Layer]
[0110] A masking layer which is used in the invention is not
particularly limited as long as the hardness HB of the masking
layer and the hardness HA of the adjacent layer satisfy Expression
(1), and a conventionally known masking layer can be appropriately
employed and used.
HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1)
[0111] The masking layer preferably contains a colorant.
[0112] As the colorant, a known colorant (organic pigment,
inorganic pigment, dye, or like) can be suitably used.
[0113] In a case where the masking layer is black, the masking
layer preferably contains a black colorant.
[0114] Examples of the black colorant include carbon black,
titanium carbon, iron oxide, titanium oxide, and black lead. Among
these, carbon black is preferable. Other than the black colorant, a
mixture of pigments such as red, blue, and green can be used.
[0115] In a case where the masking layer is white, the masking
layer preferably contains a white colorant.
[0116] As the white colorant, white pigments described in paragraph
0019 of JP2009-191118A or paragraph 0109 of JP2000-175718A can be
used. White pigments described in paragraph 0015 or 0114 of
JP2005-7765A can also be used.
[0117] Specifically, in the invention, a white inorganic pigment
such as titanium oxide (rutile type), titanium oxide (anatase
type), zinc oxide, lithophone, light calcium carbonate, white
carbon, aluminum oxide, aluminum hydroxide, or barium sulfate is
preferable, titanium oxide (rutile type), titanium oxide (anatase
type), or zinc oxide is more preferable, titanium oxide (rutile
type) or titanium oxide (anatase type) is even more preferable, and
rutile-type titanium oxide is particularly preferable.
[0118] It is desirable that the colorant is used as a dispersion
liquid.
[0119] The dispersion liquid can be prepared by adding and
dispersing a composition obtained by previously mixing the colorant
and a pigment dispersing agent in an organic solvent (or
vehicle).
[0120] Here, the vehicle refers to a medium part which disperses
the pigment in a case where the paint is in a liquid state, and
includes a component (binder) which is in a liquid state and forms
a coating film by bonding to the pigment and a component (organic
solvent) which dissolves and dilutes the above component.
[0121] The dispersing machine which is used in the dispersion of
the pigment is not particularly limited, and examples thereof
include known dispersing machines such as a kneader, a roll mill,
an attritor, a super mill, a dissolver, a homomixer, and a sand
mill described in "Pigment Dictionary", written by kunizo Asakura,
First Edition, Asakura Publishing Co., Ltd., 2000, p. 438. A
frictional force may be used for pulverizing through mechanical
grinding described in p. 310 of "Pigment Dictionary".
[0122] The number average particle diameter of the colorant is
preferably 0.001 .mu.m to 0.1 .mu.m, and more preferably 0.01 .mu.m
to 0.08 .mu.m from the viewpoint of dispersion stability.
[0123] Here, the "particle diameter" refers to a diameter in a case
where an electron microscopic image of a particle is a circle
having the same area, and the "number average particle diameter"
refers to an average of particle diameters of arbitrary 100
particles.
[0124] <Resin Composition>
[0125] The masking layer is preferably formed using a resin
composition containing a resin (binder), a polymerizable compound,
and a polymerization initiator with the above-described
colorant.
[0126] Here, as the resin material, an alkali-soluble resin is
preferable, and specifically, polymers described in paragraph
[0025] of JP2011-95716A or paragraphs [0033] to [0052] of
JP2010-237589A can be suitably used.
[0127] As the polymerizable compound, polymerizable compounds
described in paragraphs [0023] and [0024] of JP4098550B can be
used.
[0128] As the polymerization initiator or the polymerization
initiating system, polymerizable compounds described in [0031] to
[0042] of JP2011-95716A can be used.
[0129] The resin composition may further contain an additive.
Examples of the additive include surfactants described in paragraph
[0017] of JP4502784B or paragraphs [0060] to [0071] of
JP2009-237362A; thermal polymerization initiators described in
paragraph [0018] of JP4502784B; and other additives described in
paragraphs [0058] to [0071] of JP2000-310706A.
[0130] In order to produce the masking layer by coating, the resin
composition may contain a solvent, and as the solvent, solvents
described in paragraphs [0043] and [0044] of JP2011-95716A can be
used.
[0131] <Method of Forming Masking Layer>
[0132] The method of forming a masking layer is not particularly
limited, and the masking layer is preferably formed using a
transfer film which has a temporary support and a resin layer
formed using the above-described resin composition in this order.
Specifically, the masking layer is more preferably formed using a
photosensitive transfer film which has a temporary support and a
photocurable resin layer in this order, and particularly preferably
formed using a photosensitive transfer film which has a temporary
support, a thermoplastic resin layer, and a photocurable resin
layer in this order.
[0133] In a case where the masking layer is formed using a transfer
film, a colorant can be used in a resin layer. As the colorant, the
above-described colorants can be suitably used.
[0134] In a case where a transfer film is used and the masking
layer includes a photocurable resin, patterning can be performed by
a general photolithography method.
[0135] In the invention, the thickness of the masking layer is
preferably 0.5 to 10 .mu.m, and more preferably 0.8 to 5 .mu.m, and
even more preferably 1 to 3 .mu.m since the thickness of a display
device is easily reduced.
[0136] [Polymer Film]
[0137] The arbitrary polymer film which is used in the invention is
not particularly limited, and it is possible to use a polymer film
(e.g., polarizer protective film) which is generally used.
[0138] Specific examples of the polymer constituting the polymer
film include cellulose-based polymers; acrylic polymers having an
acrylic ester polymer such as polymethyl methacrylate and a lactone
ring-containing polymer; thermoplastic norbornene-based polymers;
polycarbonate-based polymers; polyester-based polymers such as
polyethylene terephthalate and polyethylene naphthalate;
styrene-based polymers such as polystyrene and an
acrylonitrile-styrene copolymer (AS resin); polyolefin-based
polymers such as polyethylene, polypropylene, and an
ethylene-propylene copolymer; vinyl chloride-based polymers;
amide-based polymers such as nylon and aromatic polyimide;
inside-based polymers; sulfone-based polymers; polyether
sulfone-based polymers; polyether ether ketone-based polymers;
polyphenylene sulfide-based polymers; vinylidene chloride-based
polymers; vinyl alcohol-based polymers; vinyl butyral-based
polymers; arlylate-based polymers; polyoxymethylene-based polymers;
epoxy-based polymers; and polymers obtained by mixing these
polymers.
[0139] Among these, cellulose-based polymers (hereinafter, may be
referred to as "cellulose acylate"), represented by triacetyl
cellulose, can be preferably used.
[0140] From the viewpoint of workability and optical performance,
acrylic polymers are also preferably used.
[0141] Examples of the acrylic polymers include polymethyl
methacrylate and lactone ring-containing polymers described in
paragraphs [0017] to [0107] of JP2009-98605A.
[0142] The thickness of the polymer film is not particularly
limited, and preferably 40 .mu.m or less since the thickness of the
polarizing plate can be reduced. The lower limit is not
particularly limited, and generally 5 .mu.m or greater.
[0143] [Hard Coat Layer]
[0144] The optical laminate according to the invention may have,
for example, a hard coat layer as an outermost layer on the visible
side.
[0145] As the material of the hard coat layer which is used in the
invention, it is possible to use a hard coat layer material which
is generally used.
[0146] In addition, the hard coat layer is preferably formed by a
crosslinking reaction or a polymerization reaction of an ionizing
radiation-curable compound.
[0147] For example, the hard coat layer can be formed by coating a
protective layer to be described later with a coating composition
containing an ionizing radiation-curable polyfunctional monomer or
polyfunctional oligomer and by crosslinking or polymerizing the
polyfunctional monomer or polyfunctional oligomer.
[0148] As the functional group of the ionizing radiation-curable
polyfunctional monomer or polyfunctional oligomer, a
photopolymerizable functional group, an electron radiation
polymerizable functional group, or a radiation polymerizable
functional group is preferable, and among these, a
photopolymerizable functional group is preferable.
[0149] Examples of the photopolymerizable functional group include
unsaturated polymerizable functional groups such as a
(meth)acryloyl group, a vinyl group, a styryl group, and an allyl
group, and among these, a (meth)acryloyl group is preferable.
[0150] In order to impart an internal scattering property, the hard
coat layer may contain mat particles having an average particle
diameter of 1.0 .mu.m to 10.0 .mu.m, and preferably 1.5 to 7.0
.mu.m, e.g., particles of an inorganic compound or a resin.
[0151] The arbitrary hard coat layer which is used in the invention
can be produced with a producing method which is generally used.
The hard coat layer may be produced by direct coating on the
above-described polarizer or polymer film, or by producing and
transferring a hard coat layer on a separate base material.
[0152] [Pressure Sensitive Adhesive Layer or Adhesive Layer]
[0153] In the optical laminate according to the invention, a
pressure sensitive adhesive or an adhesive may be used for, for
example, lamination of the above-described polarizer.
[0154] As the pressure sensitive adhesive or the adhesive, it is
possible to use a pressure sensitive adhesive (e.g., acrylic
pressure sensitive adhesive) or an adhesive (e.g.,
ultraviolet-curable adhesive, polyvinyl alcohol-based adhesive, or
the like) which is generally used.
[0155] Examples of the pressure sensitive adhesive or the adhesive
which can be used in the invention include pressure sensitive
adhesives described in paragraphs [0100] to [0115] of
JP2011-037140A or paragraphs [0155] to [0171] of
JP2009-292870A.
[0156] [Alignment Film]
[0157] The optical laminate according to the invention preferably
has an alignment film in a case where the optical laminate contains
a liquid crystal compound as an optical anisotropic layer.
[0158] The alignment film is a layer functioning to specify the
alignment direction of liquid crystal compound, and generally
contains a polymer as a main component.
[0159] Regarding a polymer material for an alignment film, there
are descriptions in many literatures, and many commercially
available products are available. As a polymer material to be used,
polyvinyl alcohols, polyimides, and derivatives thereof are
preferable. Particularly, modified or unmodified polyvinyl alcohols
are preferable. Regarding the alignment film which can be used in
the invention, modified polyvinyl alcohols described in Line 24 of
p. 43 to Line 8 of p. 49 of WO01/88574A1 or paragraphs [0071] to
[0095] of JP3907735B can be referred to. In general, the alignment
film is subjected to a known rubbing treatment. That is, in
general, the alignment film is preferably a rubbed alignment film
subjected to a rubbing treatment.
[0160] [Polarizing Plate]
[0161] A polarizing plate according to the invention is a
polarizing plate which has a polarizer, an optical anisotropic
layer, and a masking layer in this order, and in which the masking
layer is provided in a peripheral portion of a layer adjacent to
the optical anisotropic layer side of the masking layer (adjacent
layer).
[0162] In addition, the polarizing plate according to the invention
is a polarizing plate in which hardness HB of the masking layer and
hardness HA of the adjacent layer satisfy Expression (1) as in the
case of the optical anisotropic layer according to the
invention.
HA.times.0.5.ltoreq.HB.ltoreq.HA.times.2 (1)
[0163] Here, the width of the "peripheral portion" in which the
adjacent layer is provided is not particularly limited since it
depends on the sizes or the like of a gate driver and a source
driver disposed in an image display device. The width is preferably
about 1/5 to 1/100 of a length of a side of the adjacent layer
(long side in a case where the adjacent layer has a rectangular
shape). The width of the peripheral portion may be the same in all
of the sides, or may vary in some or all of the sides.
[0164] Next, an overall configuration of the polarizing plate
according to the invention will be described using FIG. 2.
[0165] FIG. 2 is a cross-sectional view schematically illustrating
an embodiment of the polarizing plate according to the
invention.
[0166] As illustrated in FIG. 2, a polarizing plate 20 has a
polarizer 1, an optical anisotropic layer 2, and a masking layer 3
in this order.
[0167] In addition, as illustrated in FIG. 2, an arbitrary polymer
film 4 may be provided between the polarizer 1 and the optical
anisotropic layer 2, and an arbitrary polymer film 5 may be
provided on a surface of the polarizer 1 on the side opposite to
the polymer film 4.
[0168] Here, the polarizer, the optical anisotropic layer, and the
masking layer of the polarizing plate according to the invention
are the same as the above-described optical laminate according to
the invention, except that the masking layer is provided in a
peripheral portion of an adjacent layer.
[0169] The polarizing plate according to the invention may have the
polymer film, the hard coat layer, the pressure sensitive adhesive
layer or adhesive layer, and the alignment film which have been
described in the optical laminate according to the invention.
[0170] As described above, the optical laminate according to the
invention also includes an aspect in which the masking layer is
formed only in a part of the adjacent layer (e.g., see FIG. 1B).
Accordingly, the polarizing plate according to the invention may be
an aspect of the optical laminate according to the invention.
[0171] [Method of Manufacturing Polarizing Plate]
[0172] The method of manufacturing a polarizing plate according to
the invention has a cutting step of cutting the above-described
optical laminate according to the invention in a thickness
direction to produce a polarizing plate.
[0173] The method of manufacturing a polarizing plate according to
the invention preferably has a patterning step of removing a part
of the masking layer in a portion which is not cut in the cutting
step before or after the cutting step.
[0174] Next, the respective steps of the method of manufacturing a
polarizing plate according to the invention will be described using
FIGS. 3 and 4.
[0175] [Cutting Step]
[0176] The cutting step is a step of cutting the above-described
optical laminate according to the invention in a thickness
direction.
[0177] Specifically, the cutting step is a step of performing
cutting of the optical laminate 10 illustrated in FIG. 1B at a
position shown by the dot-and-dash line A as illustrated in FIG. 3
to produce a polarizing plate 20.
[0178] Here, the method of cutting the optical laminate in the
thickness direction is not particularly limited, and examples
thereof include a cutting method using a rotary circular cutter
described in JP2007-260865A or JP2008-63059A; a cutting method
using a travelling blade such as a cutting plotter; a Thomson
blade-type or Pinnacle blade-type punching method using a die cut
roll; and a method of performing cutting-off up to a desired size
using a rotary body provided with a cutting blade as described in
JP2012-203209A. In this case, a plurality of optical laminates may
be simultaneously cut from the viewpoint of work efficiency.
[0179] The manufacturing method according to the invention may have
a step of smoothing an end face of the cut optical laminate after
the cutting step.
[0180] [Patterning Step]
[0181] The patterning step is an arbitrary step of removing a part
of the masking layer in a portion which is not cut in the cutting
step before or after the cutting step.
[0182] Specifically, the patterning step is a step of producing a
polarizing plate 20 by removing a part of the masking layer 3 after
cutting at a position shown by the dot-and-dash line A using the
optical laminate 10 illustrated in FIG. 1A as illustrated in FIG.
4.
[0183] FIG. 3 illustrates an aspect in which an optical laminate in
which a part of the masking layer 3 is removed by patterning before
the cutting step is used.
[0184] Here, examples of the method of removing a part of the
masking layer include a method of performing patterning by a
general photolithography method using a photosensitive transfer
film having a thermoplastic resin layer and a photocurable resin
layer as the masking layer as described above. Specifically,
exposure may be performed according to a required pattern, and then
in a case of a negative material, a non-exposed portion may be
removed, and in a case of a positive material, an exposed portion
may be removed by a development treatment to obtain a pattern. In
this case, in the development, the thermoplastic resin layer and
the photocurable resin layer may be removed by development by
different liquids, or removed by the same liquid. If necessary,
known developing equipment may be combined such as a brush or a
high-pressure jet. After the development, post-exposure or
post-baking may be performed if necessary.
[0185] [Image Display Device]
[0186] An image display device according to the invention has the
above-described polarizing plate according to the invention and a
display element.
[0187] Next, an overall configuration of the image display device
according to the invention will be described using FIG. 5, and then
configurations of the respective portions will be described in
detail.
[0188] FIG. 5 is a cross-sectional view schematically illustrating
an embodiment of the image display device according to the
invention.
[0189] As illustrated in FIG. 5, an image display device 30 has a
polarizing plate 20 and a display element 22.
[0190] In addition, as illustrated in FIG. 5, an arbitrary pressure
sensitive adhesive layer 21 may be provided between the polarizing
plate 20 and the display element 22.
[0191] [Display Element]
[0192] The display element of the image display device according to
the invention is not particularly limited, and examples thereof
include a liquid crystal panel, an organic electroluminescence (EL)
display panel, and a plasma display panel.
[0193] Among these, the display element is preferably a liquid
crystal panel or an organic EL display panel. That is, the image
display device according to the invention is preferably a liquid
crystal display device using a liquid crystal panel as a display
element or an organic EL display device using an organic EL display
panel as a display element.
[0194] [Liquid Crystal Display Device]
[0195] Examples of the liquid crystal display device which is an
example of the image display device according to the invention
include a liquid crystal display device which has a liquid crystal
panel having a liquid crystal cell and a pair of polarizing plates
between which the liquid crystal panel is interposed, and in which
at least one of the pair of polarizing plates which is disposed on
the visible side is composed of the above-described polarizing
plate according to the invention.
[0196] <Liquid Crystal Cell>
[0197] The liquid crystal cell which is used in the image display
device (liquid crystal display device) according to the invention
is preferably a vertical alignment (VA) mode, an optically
compensated bend (OCB) mode, an in-plane-switching (IPS) mode, or a
twisted nematic (TN) mode, but is not limited thereto.
[0198] In a TN mode liquid crystal cell, rod-like liquid
crystalline molecules are substantially horizontally aligned with
no voltage application thereto, and subjected to twist alignment of
60.degree. to 120.degree.. The TN mode liquid crystal cell is the
most frequently used as a color TFT liquid crystal display device,
and there are descriptions in many literatures.
[0199] In a VA mode liquid crystal cell, rod-like liquid
crystalline molecules are substantially vertically aligned with no
voltage application thereto. The VA mode liquid crystal cell may be
any one of (1) a VA mode liquid crystal cell in the narrow sense in
which rod-like liquid crystalline molecules are substantially
vertically aligned with no voltage application thereto, but are
substantially horizontally aligned in the presence of voltage
application thereto (described in JP1990-176625A (JP-H2-176625A));
(2) a multi-domain VA mode (MVA mode) liquid crystal cell for view
angle enlargement (described in SID97, Digest of tech. Papers
(proceedings) 28 (1997), 845), (3) an (n-ASM mode) liquid crystal
cell in which rod-like liquid crystalline molecules are
substantially vertically aligned with no voltage application
thereto, but are subjected to twist multi-domain alignment in the
presence of voltage Application thereto (described in proceedings
of Japan Liquid Crystal Debating Society, 58 to 59 (1998)), and (4)
a SURVIVAL mode liquid crystal cell (published in LCD International
98). In addition, the VA mode liquid crystal cell may be any one of
a patterned vertical alignment (PVA) type, an optical alignment
type, and a polymer-sustained alignment (PSA) type. The details of
the modes are described in JP2006-215326A and JP2008-538819A.
[0200] In an IPS mode liquid crystal cell, rod-like liquid crystal
molecules are aligned to be substantially parallel to the
substrate, an electric field parallel to a substrate surface is
applied, and thus the liquid crystal molecules planarly respond. In
the IPS mode, black display is performed in a state of no electric
field application, and the absorption axes of a pair of upper and
lower polarizing plates are perpendicular to each other. A method
of improving a view angle by reducing light leakage at the time of
black display in an oblique direction using an optical compensation
sheet is disclosed in JP1998-54982A (JP-1110-54982A),
JP1999-202323A (JP-H11-202323A), JP1997-292522A (JP-H09-292522A),
JP1999-133408A (JP-H11-133408A), JP1999-305217A (JP-1111-305217A),
JP1998-307291A (JP-1110-307291A), and the like.
EXAMPLES
[0201] Hereinafter, the invention will be more specifically
described based on examples. Materials, used amounts, ratios,
treatment contents, treatment sequences, and the like of the
following examples are able to be suitably changed unless the
changes cause deviance from the gist of the invention. Therefore,
the range of the invention will not be restrictively interpreted by
the following examples.
Examples 1 to 4 and Comparative Examples 1 and 2
[0202] (1) Production of Polymer Film
[0203] [Preparation of Outer Layer Cellulose Acylate Dope 1]
[0204] The following composition was put into a mixing tank and
stirred to dissolve the respective components.
[0205] Next, the obtained solution was heated for about 10 minutes
at 90.degree. C., and then filtered through filter paper having an
average pore diameter of 34 .mu.m and a sintered metal filter
having an average pore diameter of 10 .mu.m to prepare a cellulose
acylate solution 1.
TABLE-US-00001 Composition of Cellulose Acylate Solution 1
Cellulose Acetate Having Acetyl 100 parts by mass Substitution
Degree of 2.81 Polycondensation Polyester 19 parts by mass
Described in Following Table 1 Following Compound 1-1 5 parts by
mass Methylene Chloride (first solvent) 382 parts by mass Methanol
(second solvent) 57 parts by mass
TABLE-US-00002 TABLE 1 Glycol Unit Dicarboxylic Acid Unit Sealing
Average Average Rates of Number Number Number Both Ethylene of
Terephthalic Succinic of Average Terminals Glycol 1,2-Propanediol
Carbon Acid Acid Carbon Molecular (mol %) (mol %) (mol %) Atoms
(mol %) (mol %) Atoms Weight 100 50 50 2.5 55 45 6.2 1,000 mol %
Acetyl Group Compound 1-1 ##STR00001##
[0206] The following components including the cellulose acylate
solution 1 prepared as described above were put into a dispersing
machine to prepare a fine particle dispersion liquid 1.
TABLE-US-00003 Composition of Fine Particle Dispersion Liquid 1
Silica Particles Having Average 0.2 parts by mass Particle Size of
20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
Methylene Chloride (first solvent) 72.4 parts by mass Methanol
(second solvent) 10.8 parts by mass Cellulose Acylate Solution 1
10.3 parts by mass
[0207] 10 parts by mass of the prepared fine particle dispersion
liquid 1 was mixed with 100 parts by mass of the cellulose acylate
solution 1 prepared as described above to prepare an outer layer
cellulose acylate dope 1.
[0208] [Preparation of Core Layer Cellulose Acylate Dope 1]
[0209] A core layer cellulose acylate dope 1 was prepared in the
same manner as in the case of the outer layer cellulose acylate
dope 1, except that a cellulose triacetate having an acetyl
substitution degree of 2.44 was used in place of the cellulose
acetate having an acetyl substitution degree of 2.81 in the
preparation of the cellulose acylate solution.
[0210] [Production of Cellulose Acylate Film]
[0211] Three layers of a three-layer film having the core layer
cellulose acylate dope 1 as an inner layer and the outer layer
cellulose acylate dope 1 as an outer layer on both sides of the
core layer cellulose acylate dope were cast using a band casting
machine having a stainless-steel band.
[0212] The web (film) obtained by casting was peeled off from the
band, and then a pass roll was transported to perform drying for 20
minutes at a drying temperature of 120.degree. C. The drying
temperature mentioned herein refers to a film surface temperature
of the film.
[0213] After the drying, the obtained web (film) was held by a clip
and stretched in a direction (TD) perpendicular to a film transport
direction (MD) using a tenter at a stretching temperature of
189.degree. C. with a stretching ratio of 70% under uniaxial
stretching conditions at the fixed end, and a cellulose acylate
film 1 was produced.
[0214] [Coating with Organic Acid Solution]
[0215] The following compositions were mixed and cooled to
-70.degree. C. to dissolve the cellulose acetate in the solution,
and an organic acid solution 1 was prepared.
TABLE-US-00004 Composition of Organic Acid Solution 1 Cellulose
Acetate Having Acetyl 100 parts by mass Substitution Degree of 2.81
Glycerin Citric Acid Oleic Acid Ester 75 parts by mass (POEM K-37V,
manufactured by RIKEN VITAMIN Co., Ltd.) Following Compound 1-2 75
parts by mass Silica Particles Having Average 28.5 parts by mass
Primary Particle Diameter of 1.2 nm (MEK-ST, manufactured by Nissan
Chemical Industries, Ltd.) Methyl Acetate 2,237 parts by mass
Methyl Ethyl Ketone 1,864 parts by mass Propylene Glycol Monomethyl
Ether Acetate 41 parts by mass Compound 1-2 ##STR00002##
[0216] The organic acid solution 1 was applied to one surface of
the cellulose acylate film 1 after the stretching using a wire bar
coater #8 and dried for 120 seconds at 60.degree. C.
[0217] [Saponification Treatment]
[0218] The cellulose acylate film 1 coated with the organic acid
solution 1 was immersed in a sodium hydroxide aqueous solution of
2.3 mol/L for 3 minutes at 55.degree. C.
[0219] Next, the film was washed in a water washing bath at room
temperature and neutralized using a 0.05 mol/L sulfuric acid at
30.degree. C. Then, the film was washed again in the water washing
bath at room temperature and dried with hot air at 100.degree.
C.
[0220] In this manner, a saponification treatment was performed on
the surface (both sides) of the cellulose acylate, film 1.
[0221] The thickness of the obtained cellulose acylate film 1 was
39 .mu.m.
[0222] (2) Formation of Interlayer
[0223] The following compositions were mixed to prepare an
interlayer coating liquid 1.
[0224] The prepared interlayer coating liquid 1 was applied to a
surface of the cellulose acylate film 1 obtained as described
above, on the side opposite to the surface coated with the organic
acid solution 1, using a wire bar coater #1.6.
[0225] Next, after drying for 30 seconds at a film surface
temperature of 60.degree. C., ultraviolet irradiation was performed
for 30 seconds at 30.degree. C. using a high-pressure mercury lamp
of 120 W/cm to crosslink an interlayer.
[0226] The thickness of the obtained interlayer was 0.6 .mu.m.
TABLE-US-00005 Composition of Interlayer Coating Liquid 1 Following
Acrylic Compound Mixture 100 parts by mass Photopolymerization
Initiator 4 parts by mass (IRGACURE 127, manufactured by BASF SE)
Cyclohexanone 589 parts by mass
[0227] As the acrylic compound mixture, a mixture in which the mass
ratio (ACR1/ACR2) between the following ACR1 and ACR2 was 67/33 was
used.
[0228] ACR1: BLEMMER GLM (manufactured by NOF CORPORATION, compound
having the following structure)
##STR00003##
[0229] ACR2: KAYARAD PET30 (manufactured by Nippon Kayaku Co.,
Ltd., mixture of compounds having the following structure
(pentaerythritol triacrylate/pentaerythritol tetraacrylate))
##STR00004##
[0230] (3) Formation of Optical Anisotropic Layer
[0231] The following compositions were mixed and dissolved to
prepare an optical anisotropic layer coating liquid A.
[0232] The optical anisotropic layer coating liquid A was applied
to the interlayer of the cellulose acylate film formed up to the
interlayer using a wire bar #3.2.
[0233] The film was attached to a metal frame and heated for 2
minutes in a constant-temperature tank at 100.degree. C. to align
the liquid crystal compound (homeotropic alignment).
[0234] Next, after cooling at 50.degree. C., ultraviolet
irradiation was performed at an irradiation dose of 300 mJ/cm.sup.2
and an illuminance of 190 mW/cm.sup.2 using an air-cooled metal
halide lamp (manufactured by EYE GRAPHICS Co., Ltd.) of 160 W/cm at
an oxygen concentration of about 0.1% under nitrogen purge to cure
an optical anisotropic layer A.
[0235] The thickness of the optical anisotropic layer A was 1.3
.mu.m. Re of the optical anisotropic layer A at a wavelength of 550
nm was 0 nm, and Rth of the optical anisotropic layer at a
wavelength of 550 nm was -165 nm.
TABLE-US-00006 Composition of Optical Anisotropic Layer Coating
Liquid A Liquid Crystal Compound (following B01) 72 parts by mass
Liquid Crystal Compound (following B02) 18 parts by mass
Photopolymerization initiator (IRGACURE 907, manufactured by BASF
SE) 3 parts by mass Sensitizer (KAYACURE DETX, manufactured by
Nippon Kayaku Co., Ltd.) 1 part by mass Vertical Alignment Agent
(following S01) 0.1 parts by mass Methyl Ethyl Ketone 397 parts by
mass Cyclohexanone 64 parts by mass B01 ##STR00005## B02
##STR00006## S01 ##STR00007##
[0236] (4) Formation of Masking Layer
[0237] Coating liquids K-1, to K-6 for a masking layer were
prepared as shown in the following Table 2.
TABLE-US-00007 TABLE 2 Coating Liquid For Masking Layer Material
K-1 K-2 K-3 K-4 K-5 K-6 Pigment Dispersion K-Pigment Dispersion
(solid 31.20 31.20 31.20 31.20 31.20 31.20 content: 20.47%)
R-Pigment Dispersion (solid 3.30 3.30 3.30 3.30 3.30 3.30 content:
30%) Photopolymerizable Tricyclodecane Dimethanol 1.80 Compound
Diacrylate A-DCP Urethane Acrylate UA-306H 7.48 12.88 Urethane
Acrylate U-200PA 7.48 12.88 DPHA Liquid 5.50 4.88 Binder Binder Z
10.80 7.50 7.50 2.10 2.10 Compound A 7.50 Polymerization
2,4-Bis(trichloromethyl)-6-[4'-(N,N- 0.40 0.40 0.40 0.40 0.40 0.40
Initiator bis(ethoxycarbonylmethyl)amino-3'-
bromophenyl]-s-triazine Polymerization Phenothiazine 0.01 0.01 0.01
0.01 0.01 0.01 Inhibitor Thermal Crosslinking DURANATE TPA-B80E
2.00 Agent Coating Auxiliary MEGAFAC F780 0.10 0.10 0.10 0.10 0.10
0.10 Agent (manufactured by DIC Corporation) Solvent Methyl Ethyl
Ketone 33.99 34.11 35.31 35.31 35.31 35.31 Propylene Glycol
Monomethyl 6.20 6.20 6.20 6.20 6.20 6.20 Ether Acetate
Cyclohexanone 8.50 8.50 8.50 8.50 8.50 8.50 Total (parts by mass)
100 100 100 100 100 100
[0238] In the above Table 2, details of the K-pigment dispersion
and the like are as follows.
TABLE-US-00008 Composition of K-Pigment Dispersion Carbon Black
(trade name: Nipex 35, manufactured by EVONIK) 13.1 parts by mass
Following Dispersing Agent 1 0.65 parts by mass Binder 1 (random
copolymer having molar ratio of benzyl methacrylate to 6.72 parts
by mass methacrylic acid of 72/28, weight average molecular weight
3.70000) Propylene Glycol Monomethyl Ether Acetate 79.53 parts by
mass Dispersing Agent 1 ##STR00008##
TABLE-US-00009 Composition of R-Pigment Dispersion Pigment (C. I.
Pigment Red 177) 18 parts by mass Binder 1 (random copolymer having
molar ratio of benzyl methacrylate to 12 parts by mass methacrylic
acid of 72/28, weight average molecular weight 3.70000) Propylene
Glycol Monomethyl Ether Acetate 70 parts by mass Tricyclodecane
Dimethanol Diacrylate A-DCP: manufactured by SHIN.NAKAMURA CHEMICAL
CO., L:17D. Urethane Acrylate UA-306H: manufactured by KYOEISHA
CHEMICAL Co., LTD. Urethane Acrylate U-200PA: manufactured by
SRN-NAKAMURA CHEMICAL CO., ETD. DPHA Liquid: Mixed liquid of 38
mass % of dipentaerythritol hexaacrylate, 38 mass % of
dipentaerythritol pentaarrylate, and 24 mass % of
1-methoxy-2-propyl acetate Binder Z: Random copolymer (weight
average molecular weight 3.80000) having molar ratio of benzyl
methacrylate to methacrylic acid of 78/22 Structural Formula of
Compound A (acid value: 96 mgKOH/g) (in the following formula,
x/l/y/z = 46/2/32/20) ##STR00009## Phenothiazine: manufactured by
Wako Pure Chemical Industries, Ltd. DURANATE TPA-B80E: manufactured
by Asahi Kasei Corporation MEGAFAC F780: manufactured by DIC
Corporation
[0239] The prepared coating liquids K-1 to K-6 for a masking layer
were respectively applied to the optical anisotropic layer A formed
as described above, and dried to obtain laminates 1 to 6 having a
masking layer having a thickness of 2.2 .mu.m.
[0240] (5) Production of Optical Laminate
[0241] First, stretching was performing in a longitudinal direction
with a circumferential speed difference given between two pairs of
nip rolls according to Example 1 of JP2001-141926A, and a polarizer
having a width of 1,330 mm and a thickness of 15 .mu.m was
produced. The polarizer produced in this manner was used as a
polarizer 1.
[0242] Next, each of the laminates produced previously was stuck to
the polarizer 1 using an adhesive.
[0243] In this case, a surface of the cellulose acylate film of the
laminate coated with the organic acid solution 1 was stuck to the
polarizer 1.
[0244] Next, to a surface of the polarizer 1 on the opposite side
(surface which was not stuck to the laminate), FUJITAC TD80
(manufactured by Fujifilm Corporation) was stuck to produce optical
laminates 1 to 6.
[0245] (6) Patterning of Masking Layer
[0246] Pattern exposure was performed from the masking layer side
with an exposure amount of 200 mJ/cm.sup.2 (i-ray) at an
illuminance of 30 mW/cm.sup.2 (i-ray) on the optical laminates 1 to
6 with a distance of 200 .mu.m between a surface of an exposure
mask (quartz exposure mask having a pattern for forming a masking
layer) and a surface of the optical laminate on the masking layer
side by using a proximity-type exposure machine (manufactured by
Hitachi High-Technologies Corporation) having a ultrahigh-pressure
mercury lamp.
[0247] After the exposure, development was performed for 45 seconds
at a shower pressure set to 0.1 MPa at 32.degree. C. using a sodium
carbonate/sodium hydrogen carbonate-based developer (liquid
obtained by diluting T-CD1 (trade name) (manufactured by Fujifilm
Corporation) five times with pure water), and washing was performed
with pure water. Next, the moisture of the surface of the optical
laminate was removed by blowing air.
[0248] Next, using the above-described proximity-type exposure
machine, the entire surface was exposed without the mask with an
exposure amount of 1,000 mJ/cm.sup.2 (i-ray).
[0249] Then, a post-baking treatment was perforated for 30 minutes
at 145.degree. C., and the optical laminates 1 to 6 having a
patterned masking layer, that is, polarizing plates 1 to 6 were
obtained.
[0250] <Hardness>
[0251] Regarding the optical laminates and the polarizing plates
produced in Examples 1 to 4 and Comparative Examples 1 and 2,
hardness HB of the masking layer and hardness HA of the optical
anisotropic layer adjacent to the masking layer were measured by
the above-described measurement method using a microhardness tester
(HM-2000, manufactured by FISCHER INSTRUMENTS K.K.). The results
thereof are shown in the following Table 3. The hardness in the
optical laminate and the hardness in the polarizing plate were the
same values.
[0252] <Workability (Presence or Absence of Occurrence of
Cracks)>
[0253] The optical laminates produced in Examples 1 to 4 and
Comparative Examples 1 and 2 were cut into a desired size by a
cutting plotter, and workability thereof was evaluated.
[0254] Specifically, 20 A4-sized samples were cut from each optical
laminate, and their appearance, especially, a space between the
masking layer and the layer adjacent to the masking layer (optical
anisotropic layer) was visually confirmed to confirm the presence
or absence of the occurrence of cracks.
[0255] An optical laminate in which it was possible to confirm the
occurrence of cracks in two or more of 20 samples was evaluated as
"B" as an optical laminate having poor workability; and an optical
laminate in which it was not possible to confirm the occurrence of
cracks and an optical laminate in which it was possible to confirm
the occurrence of cracks in only one sample were evaluated as "A"
as an optical laminate having excellent workability.
TABLE-US-00010 TABLE 3 Comparative Examples Examples 1 2 3 4 1 2
Coating Liquid for K-1 K-2 K-3 K-4 K-5 K-6 Masking Layer Hardness
HA 223 223 223 223 223 223 of Optical Anisotropic Layer
(N/mm.sup.2) Hardness HB of 206 242 347 121 463 52 Masking Layer
(N/mm.sup.2) Workability A A A A B B
[0256] From the results shown in Table 3, it was found that in
Comparative Examples 1 and 2 in which the hardness HB of the
masking layer was out of the range ranging from 0.5 times to 2.0
times the hardness HA of the optical anisotropic layer, the optical
laminate had poor workability.
[0257] However, it was found that in Examples 1 to 4 in which the
hardness HB of the masking layer was within the range ranging from
0.5 times to 2.0 times the hardness HA of the optical anisotropic
layer, the optical laminate had excellent workability and it was
possible to suppress the occurrence of cracks in the polarizing
plate.
[0258] <Production of Liquid Crystal Display Device>
[0259] A commercially available liquid crystal display device (iPad
(registered trademark, the same hereinafter) manufactured by Apple
Inc.) in which a polarizing plate on the visible side was peeled
off from a liquid crystal cell was used as an WS mode liquid
crystal cell.
[0260] In place of the peeled polarizing plate, the polarizing
plate produced as described above was stuck to the liquid crystal
cell, and each liquid crystal display device was produced.
[0261] In this case, the polarizing plate was stuck to the liquid
crystal cell such that an absorption axis of the polarizing plate
was perpendicular to an optical axis of the liquid crystal layer in
the liquid crystal cell when observed in a direction perpendicular
to the substrate surface of the liquid crystal cell.
[0262] The liquid crystal display device in which the polarizing
plate was stuck to the liquid crystal cell was operated and
confirmed to be operated without problems.
Example 5
[0263] (1) Production of Polymer Film
[0264] [Preparation of Core Layer Cellulose Acylate Dope 2]
[0265] The following compositions were put into a mixing tank and
stirred to dissolve the respective components, and a core layer
cellulose acylate dope 2 was prepared.
TABLE-US-00011 Cellulose Acetate Having Acetyl Substitution 100
parts by mass Degree of 2.38 Ester Oligomer (following compound
1-1) 10 parts by mass Durability Improver (following compound 1-2)
4 parts by mass Ultraviolet Absorbing Agent 3 parts by mass
(following compound 1-3) Methylene Chloride (first solvent) 438
parts by mass Methanol second solvent) 65 parts by mass (Compound
1-1) ##STR00010## (Compound 1-2) ##STR00011## (Compound 1-3)
##STR00012## (Compound 1-1)
[0266] [Preparation of Outer Layer Cellulose Acylate Dope 2]
[0267] 10 parts by mass of the following matting agent dispersion
liquid 1 was added to 190 parts by mass of the core layer cellulose
acylate dope 2 prepared as described above to prepare an outer
layer cellulose acylate dope 2.
TABLE-US-00012 Silica Particles Having Average 2 parts by mass
Particle Size of 20 nm (AEROSIL R972, manufactured by Nippon
Aerosil Co., Ltd.) Methylene Chloride (first solvent) 76 parts by
mass Methanol (second solvent) 11 parts by mass Core Layer
Cellulose Acylate Dope 2 1 part by mass
[0268] [Production of Cellulose Acylate Film 2]
[0269] Three layers of a three-layer film having the core layer
cellulose acylate dope 2 as an inner layer and the outer layer
cellulose acylate dope 2 as an outer layer on both sides of the
core layer cellulose acylate dope were simultaneously cast on a
drum at 20.degree. C. from a casting outlet.
[0270] Next, the film was stripped off from the drum in a state in
which the solvent content was about 20 mass %. The film was fixed
at both ends thereof in a width direction (direction (TD)
perpendicular to the transport direction (MD)) of the film by a
tenter clip, and in a state in which the residual solvent was 3 to
15 mass %, the film was dried while being stretched 1.2 times in
the width direction.
[0271] Then, the film was transported between rolls of a heat
treatment device, and thus a cellulose acylate film 2 having a
thickness of 25 .mu.M was produced.
[0272] (2) Production of Hard Coat Layer
[0273] A curable composition hard coating 1 for a hard coating
described in the following Table 4 was prepared as a coating liquid
for forming a hard coat layer.
TABLE-US-00013 TABLE 4 Monomer Total UV Initiator Amount Added
Monomer Added Amount 1/Monomer [parts by [parts by Monomer 1
Monomer 2 2 mass] Type mass] Solvent Hard Pentaerythritol
Pentaerythritol 3/2 53.5 UV 1.5 Ethyl Coating 1 triacrylate
tetraacrylate Initiator 1 Acetate (Compound 2-1) ##STR00013##
UV Initiator 1
[0274] The hard coating 1 was applied to a surface of the cellulose
acylate film 2 produced as described above, and then dried for 60
seconds at 100.degree. C. and subjected to ultraviolet irradiation
for curing under the conditions of 1.5 kW, 300 mJ, and 0.1% or less
of nitrogen to produce a cellulose acylate film 2 with a hard coat
layer having a thickness of 5 pin.
[0275] The thickness of the hard coat layer was adjusted by
adjusting the coating amount in the die coating method using a slot
die.
[0276] (3) Production of Polarizer
[0277] Stretching was performing in a longitudinal direction with a
circumferential speed difference given between two pairs of nip
rolls according to Example 1 of JP2001-141926A, and a polarizer
having a width of 1,330 mm and a thickness of 15 .mu.m was
produced. The polarizer produced in this manner was used as a
polarizer 2.
[0278] (4) Lamination of Polarizer
[0279] The produced cellulose acylate film 2 with a hard coat layer
was immersed for 1 minute in a sodium hydroxide aqueous solution
(saponification liquid) of 4.5 mol/L, having a temperature adjusted
to 37.degree. C. Then, the film was washed with water. Thereafter,
the film was immersed for 30 seconds in a sulfuric acid aqueous
solution of 0.05 mol/L, and then passed through a water washing
bath. Dewatering was repeated three times by an air knife, and
after the dropping of water, the film was dried by being kept for
15 seconds in a drying zone at 70.degree. C. to produce a cellulose
acylate film 2 with a saponified hard coat layer.
[0280] The polarizer 2 produced as described above and the
cellulose acylate film 2 with a saponified hard coat layer were
stuck to each other in a roll-to-roll manner using an aqueous
solution of 3% PVA (manufactured by KURARAY COL., LTD., PVA-117H)
as an adhesive such that a polarization axis is perpendicular to
the longitudinal direction of the film, and thus a laminate 7 was
produced.
[0281] In this case, the cellulose acylate film was stuck so as to
be on the polarizer side.
[0282] (5) Formation of First Optical Anisotropic Layer
[0283] A surface of the laminate 7 on the side of the polarizer 2
was subjected to a rubbing treatment in a direction perpendicular
to the absorption axis of the polarizer 2. The following coating
liquid B for an optical anisotropic layer was applied to the
surface subjected to the rubbing treatment using a bar coater with
a bar number #2.4.
[0284] Next, heat aging was performed for 30 seconds at a film
surface temperature of 60.degree. C., and then 290 mJ/cm.sup.2 of
ultraviolet irradiation was performed using an air-cooled metal
halide lamp (manufactured by EYE GRAPHICS Co., Ltd.) in the air at
a film surface temperature of 60.degree. C. to fix the alignment
state, and thus a first optical anisotropic layer was formed.
[0285] In the formed first optical anisotropic layer, the rod-like
liquid crystal compound was horizontally aligned, and the slow axis
direction was a direction parallel to the rubbing direction, that
is, perpendicular to the absorption axis direction of the
polarizer. Light incident angle dependence of each of Re and Rth
was measured using an automatic birefringence index meter
(KOBRA-21ADH, manufactured by Oji Scientific Instruments) Re was
128 nm and Rth was 64 nm at a wavelength of 550 nm.
TABLE-US-00014 Composition of Coating Liquid B tbr Optical
Anisotropic Layer Rod-Like Liquid Crystal Compound 1 80 parts by
mass Rod-Like Liquid Crystal Compound 2 20 parts by mass
Photopolymerization Initiator 1 (IRGACURE 907, manufactured by BASF
SE) 3.0 parts by mass Sensitizer (KAYACURE DETX, manufactured by
Nippon Kayaku Co., Ltd.) 1.0 part by mass Fluorine-Containing
Compound A 0.8 parts by mass Methyl Ethyl Ketone 213 parts by mass
Rod-Like Liquid Crystal Compound 1 ##STR00014## Rod-Like Liquid
Crystal Compound 2 ##STR00015## Photopolymerization Initiator 1
##STR00016## Sensitizer ##STR00017## Fluorine-Containing Compound A
##STR00018##
[0286] (6) Formation of Alignment Film.
[0287] An alignment film coating liquid having the following
composition was applied to a surface of the first optical
anisotropic layer produced as described above using a wire bar #14.
The alignment film coating liquid was dried for 120 seconds with
hot air at 60.degree. C. to form an alignment film.
TABLE-US-00015 Composition of Alignment Film Coating Liquid
Following Modified Polyvinyl Alcohol 10 parts by mass Water 245
parts by mass Methanol 245 parts by mass Glutaraldehyde 0.5 parts
by mass Modified Polyvinyl Alcohol ##STR00019##
[0288] (7) Production of Second Optical Anisotropic Layer
[0289] The following coating liquid C for an optical anisotropic
layer was applied to the alignment film using a bar coater with a
bar number #2.4.
[0290] Next, heat aging was performed for 30 seconds at a film
surface temperature of 60.degree. C., and then 290 mJ/cm.sup.2 of
ultraviolet irradiation was performed using an air-cooled metal
halide lamp (manufactured by EYE GRAPHICS Co., Ltd.) in the air at
a film surface temperature of 60.degree. C. to fix the alignment
state, and thus a second optical anisotropic layer was formed.
[0291] In the formed second optical anisotropic layer, the rod-like
liquid crystal compound was vertically aligned. Light incident
angle dependence of each of Re and Rth was measured using an
automatic birefringence index meter (KOBRA-21ADH, manufactured by
Oji Scientific Instruments), Re was 0 and Rth was -115 nm at a
wavelength of 550 nm.
TABLE-US-00016 Composition of Coating Liquid C for Optical
Anisotropic Layer Rod-Like Liquid Crystal Compound 1 80 parts by
mass Rod-Like Liquid Crystal Compound 2 20 parts by mass
Photopolymerization Initiator 1 (IRGACURE 907, manufactured by BASF
SE) 3.0 parts by mass Sensitizer (KAYACURE DETX, manufactured by
Nippon Kayaku Co., Ltd.) 1.0 part by mass Following
Fluorine-Containing Compound B 0.8 parts by mass Following Vertical
Alignment Agent 1 1.0 part by mass Following Adhesion Enhancing
Agent 1 0.25 parts by mass Methyl Ethyl Ketone 251 parts by mass
Fluorine-Containing Compound B ##STR00020## Vertical Alignment
Agent 1 ##STR00021## Adhesion Enhancing Agent 1 ##STR00022##
[0292] (8) Formation of Masking Layer
[0293] The coating liquid K-1 for a masking layer prepared in
Example 1 was applied to the second optical anisotropic layer
formed as described above, and was dried to obtain an optical
laminate 7 having a masking layer having a thickness of 2.2
.mu.m.
[0294] (9) Patterning of Masking Layer
[0295] Pattern exposure was performed with an exposure amount of
200 mJ/cm.sup.2 (i-ray) at an illuminance of 30 mW/cm.sup.2 (i-ray)
on the optical laminate 7 with a distance of 200 .mu.m between a
surface of an exposure mask (quartz exposure mask having a pattern
for forming a masking layer) and a surface of the optical Laminate
on the masking layer side by using a proximity-type exposure
machine (manufactured by Hitachi High-Technologies Corporation)
having a ultrahigh-pressure mercury lamp.
[0296] After the exposure, development was performed for 45 seconds
at a shower pressure set to 0.1 MPa at 32.degree. C. using a sodium
carbonate/sodium hydrogen carbonate-based developer (liquid
obtained by diluting T-CD1 (trade name) (manufactured by Fujifilm
Corporation) five times with pure water), and washing was performed
with pure water. Next, the moisture of the surface of the optical
laminate was removed by blowing air.
[0297] Next, using the above-described proximity-type exposure
machine, the entire surface was exposed without the mask with an
exposure amount of 1,000 mJ/cm.sup.2 (i-ray). Finally, a
post-baking treatment was performed for 30 minutes at 145.degree.
C., and thus a polarizing plate 7 having a patterned masking layer
was obtained.
[0298] <Hardness and Workability>
[0299] Regarding the produced optical anisotropic layer 7, the
hardness was measured and the workability was evaluated in the same
manner as in Example 1.
[0300] As a result, the hardness HB of the masking layer was 206
N/mm.sup.2, and the hardness HA of the second optical anisotropic
layer adjacent to the masking layer was 228 N/mm.sup.2.
[0301] In the workability evaluation, it was found that the
workability was evaluated to be A since the occurrence of cracks
was not confirmed.
[0302] <Production of Liquid Crystal Display Device>
[0303] A liquid crystal display device was produced in which
polarizing plates on the visible side and on the backlight side
were peeled off from the liquid crystal cell of a commercially
available liquid crystal display device (iPad, manufactured by
Apple Inc.), the above-described polarizing plate 7 was used as the
polarizing plate on the visible side, the following polarizing
plate 8 was used as the polarizing plate on the backlight side, and
the polarizing plates were stuck such that absorption axes of the
polarizers included in the respective polarizing plates were
perpendicular to each other.
[0304] The liquid crystal display device in which the polarizing
plates were stuck to the liquid crystal cell was operated and
confirmed to be operated without problems.
[0305] (Polarizing Plate 8)
[0306] A laminate produced in the same manner as in the case of the
laminate 7, except that no hard coat layer was provided in the
production of the laminate 7, was used as the polarizing plate
8.
EXPLANATION OF REFERENCES
[0307] 1: polarizer [0308] 2: optical anisotropic layer [0309] 3:
masking layer [0310] 4, 5: polymer film [0311] 10: optical laminate
[0312] 20: polarizing plate [0313] 21: pressure sensitive adhesive
layer [0314] 22: display element [0315] 30: image display
device
* * * * *